Question

An element (X) forms compounds of the formula $XC{l}_3,X_2{O}_5$ and $C{a}_3{X}_2$, but does not form $XC{l}_5$. Which of the following is the element?

• A. B
• B. Al
• C. N
• D. P

Answer 1

The correct option is C N

Nitrogen forms $NC{I}_3,N_2{O}_5$ and $C{a}_3{N}_2$.

Nitrogen due to absence of empty d-orbitals, cannot extend its covalency by more than three and hence do not form $NC{l}_5$. Due to its small size and high electronegativity it can accept 3 electrons to form $N^{3-}ion\left(C{a}_3{N}_2\right)$.

Hence, the correct option is $C$.